1. Technical Field
The present invention relates to a liquid crystal device and an electronic apparatus that are provided with viewing angle control function of switching a wide viewing angle visible state and a narrow viewing angle visible state.
2. Related Art
Currently, a liquid crystal device is widely used in an electronic apparatus, such as a cellular phone, a personal digital assistants, or a computer display. For example, the liquid crystal device is used for displaying various pieces of information regarding an electronic apparatus as an image. In regard to this liquid crystal device, a wide viewing angle characteristic may be required or a narrow viewing angle characteristic may also be required.
When a large number of people view an image that is displayed on the liquid crystal device from multi-directions, a wide viewing angle is required. On the other hand, when a user does not want others to look in a display image while viewing the display image, a narrow viewing angle characteristic is required, for example, when viewing an image that is displayed on a cellular phone in a crowded place. To meet the above request, an existing liquid crystal device that can be used by switching between a wide viewing angle and a narrow viewing angle has been proposed.
For example, a liquid crystal device that adds a viewing angle control element, which is formed of a liquid crystal panel, to a display element, such as the liquid crystal device, has been known. The liquid crystal device is, for example, described in Japanese Unexamined Patent Application Publication No. 2004-361917, Japanese Unexamined Patent Application Publication No. 2005-275342, Japanese Unexamined Patent Application Publication No. 2006-064882, Japanese Unexamined Patent Application Publication No. 2006-072239, and Japanese Unexamined Patent Application Publication No. 2006-106439. The liquid crystal devices described in the above publications achieve a narrow viewing angle by darkening a display when a viewing angle control element is viewed from an inclined direction (that is, a direction in which a polar angle is large). In addition, an existing technology for switching between a wide viewing angle and a narrow viewing angle has been known, in which two types of light sources having different light diffusion properties or light directivity within a backlight, and a wide viewing angle and a narrow viewing angle are switched by switching those light sources.
Furthermore, in recent years, a configuration of a liquid crystal device has been proposed, in which viewing angle control pixels that are driven by a vertical electric field are assembled into display pixels of the liquid crystal panel of the liquid crystal device that employs a lateral electric field driving mode, which is typically represented by an IPS (In-Plain Switching) mode or an FFS (Fringe Field Switching) mode, which is, for example, described in H. S. Jin et al. “Novel Viewing-Angle Controllable TFT-LCD”, SID (Society for Information Display) 06 DIGEST P-139 (hereinafter, referred to as Non-Patent Document 1).
In the liquid crystal device described in Non-Patent Document 1, by switching viewing angle control pixels between an on state and an off state, viewing angle control is performed for restricting an image display that is performed in a lateral electric field mode to a narrow viewing angle or allowing an image to be displayed as it is. This viewing angle control does not require another liquid crystal panel for viewing angle compensation in addition to a liquid crystal panel for display, and has advantage such that viewing angle compensation can be performed only by a single liquid crystal panel. However, in the above Non-Patent Document 1, it is necessary to provide electrodes respectively for a pair of substrates opposite each other in order to form a vertical electric field within the viewing angle control pixels and, therefore, there is a problem that an electrode structure and a wiring structure are complex in the pair of substrates. In addition, there is also a problem that an occurrence of assembly deviation when the pair of substrates are adhered should be strictly regulated.